Carbon Composites Are Becoming Competitive And Cost …

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CARBON COMPOSITES ARE BECOMING COMPETITIVE AND COST EFFECTIVE

- Shama Rao N., Simha T. G. A., Rao K. P. and Ravi Kumar G. V. V.

Abstract

Carbon Fiber Reinforced Composites are widely used in multiple industries due to its high performance although the cost is higher compared to metals. However, recent advances in composites are driving carbon composites to be more competitive and cost effective. The reduction of defects and cycle time realized by the introduction of high-end processes is accelerating this pace further. New technological developments in fiber reinforcements, resin systems, and production concepts are continuing to drive the future deployment. This paper presents a perspective on how carbon composites are becoming more competitive and cost effective across industries. The influence of various advanced technologies in reducing the cost of carbon composites is also presented.

1. Introduction

Composites have been widely used across industries like aerospace, wind energy, automotive, industrial, marine, oil and gas. Advanced carbon fiber composites are comparatively more expensive than metals. The choice of composites is a tradeoff between cost and performance. As a result, carbon composites have made their impact in high performance vehicles, such as, jet fighters, spacecraft, racing cars, racing yachts and exotic sports cars. The global composites materials market is about $28Bn in 2014 and is growing at 1520% per year. This market size will further grow provided the cost of composites is reduced. The cost considered is primarily the composite manufacturing cost. However, for correct assessment entire life cycle cost need to be considered including maintenance and operation. Composites provide a cost benefit particularly in respect of operation and maintenance which form a sizable percentage of direct operating cost.

A typical cost comparison between various materials is shown in Figure 1 and Figure 2 presents the worldwide market estimates for carbon fiber. Although, the cost of carbon fibers is high, the market for carbon fiber in non-aerospace structures is increasing at a rapid rate as shown in Figure 3.

Cost of the product is the major factor prohibiting the wide spread use of carbon composites in industry. The following factors contribute to reduction of cost

? Reduction in cost of carbon fiber ? Availability of high performance

resins meeting production automation requirements

? Cost effective product forms ? Cost effective production methods

and automation with repeatable high quality

? Availability of relevant design and

environment data on selected composite systems

? High-volume processing

External Document ? 2018 Infosys Limited

Figure 1. Cost Comparison of Materials Figure 2. Global Consumption Carbon Fiber (2012)

Figure 3. Trends and Forecast of Carbon fiber

2. Recent Advancements in Polymer Matrix Composites

The effort to produce economically attractive composite components has resulted in several invetive manufacturing techniques. It is obvious that improvement in manufacturing technology alone is not enough to overcome the cost hurdle. It is essential that there be an integrated effort of key cost drivers as shown in the figure 4 for composites to become competitive with metals.

Raw Materials

Main raw materials of carbon composites are polymeric resins and carbon fibers. Cost of carbon fiber is directly related to the cost and yield of precursor from which it is obtained and cost of conversion. At present carbon fiber is Polyacrylonitrile (PAN) based and its average cost of nonaerospace grade is around $21.5/kg, with a conversion efficiency of only 50%.

The following advances are taking place to reduce the cost of carbon fiber:

? Development of low cost and high

yield precursors for manufacture of commercial (heavy-tow) carbon fibers which will significantly reduce the carbon fiber cost. Industrial grade fibers are expected to be available at $13.8/kg by 2017. Figure 3 shows how the cost of carbon fiber is going to get reduced in future, till the year 2020, due to some of these advances in raw materials.

? Chopped carbon fiber/epoxy prepregs

in Sheet Molding Compound (SMC) form for structural applications with processing times in minutes with 3-D molding capability that results in dimensionally controlled surfaces on both sides.

? Development of highly moldable

fast cycle prepregs, uni-directionally arrayed chopped strand prepregs

? Development of highly reactive resins

to reduce cycle time

? Combining fibers to create hybrids and

weaving forms, re-use of waste fibers by combining and consolidating dry fibers into a mat

? Development in preform technology:

multi-ply curved complex preforms such as skin-stringer / frame intersections.

Advanced Software Tools Production Technology Raw materials

Cost Reduction

Figure 4. Key drivers for Cost reduction

Production Technologies

Many advanced production technologies are in good state of development. These have potential to reduce the manufacturing and assembly costs while capable of meeting the production volumes of specific industries. Some of them are:

? Fast cycle manufacturing techniques ? Lay-up automation and automation of

labour intensive activities

? Flexible automated composite

laying processes

? Textile processes like braiding ( 3-D)

and preform making,

? Forming processes ? Out of autoclave processes like resin

transfer molding and resin infusion technology

? Utilization of Fluid based pressure/

heating/cooling systems

? High speed compression molding ? High pressure molding process -

method of forging net shaped parts from prepreg bundles similar to metal forging.

? Rapid cure resin technology combined

with RTM for fabrics curing in 10 minutes.

Advanced Software Tools for Composite Product Development

Many advanced composite software tools and utilities are now available to automate many engineering processes and to reduce design cycle time. These tools identify feasibility of manufacturing and associated issues upfront during design stage. These advanced software tools are helping to perform many engineering activities concurrently while reducing the design cycle time and engineering cost. Few of these tools include:

? Advanced design, analysis and

manufacturing simulation software tools and utilities

? Knowledge Based Engineering Tools ? Design for part integration and co-cure

methods

? Design integrated virtual

manufacturing software systems

? Cost modeling software.

External Document ? 2018 Infosys Limited

3. Industry Specific Advances in Carbon Composites

Aerospace Industry

Recent advances in aerospace structure are:

? Production of carbon fibers from Textile

PAN and / or melt spun PAN likely (cost reduction by 15% to 20%)

? Dry composite preforms, woven

structural braided reinforcements, complex textile based architecture associated with out- of- auto clave curing such as RTM/Resin infusion and e-beam curing

? Availability of high performance fast

curing resins to meet the out-ofautoclave production processes.

? Automated Dry Material Placement

(ADMP) ? A newer approach to cut and place ply patterns in one operation eliminating pick up and placement approach.

? CNC controlled contour tape laying/

fiber placement machines with high deposition rates

? Manufacture of large parts through

Vacuum-Assisted Process (VAP) and combined infusion of the different parts (skin and stringers), avoiding thousands of rivets and secondary operations.

? On-line quality control during

manufacturing process

? Designing with heavy tows of

uni-directional materials without compromising properties.

? Custom built dry fiber tapes with

suitable binders, designed to be used on current AFP machines to create dry Preforms

? Development in Preforms using many

passes of narrow bands of dry tape that are consolidated as it is placed

Automotive Industry

Recent advances in different areas of composites in automotive industry can be summarized into Raw material:

? Technological advances in the area

of low-cost fiber precursors such as, cheaper polymers, inexpensive textiles, low-quality plant fibers or renewable natural fibers to meet auto requirements in terms of properties.

? Novel carbonization techniques

to produce useful, uniform fiber properties at low cost

Materials and forms:

? Multi-material system and Hybrids-

carbon and glass

? Carbon /Epoxy SMCs ? New and faster curing resins ? Combination of material forms like

chopped fibers with continuous fibers tailored to meet the requirement

? Stronger and durable adhesives

Design:

? Advances in CAE ? Change in mindset of designers ? Better integration methods with metals

Rapid economic fabrication processes capable of achieving high volume cost effective structures:

? High speed Compression Molding

? Compression molding of pre-pregs ? High speed resin transfer molding

? Resin spray transfer molding

? Reactive injection molding

Joining -fastening and bonding

? Design criteria and design

methodologies

? Tailoring of adhesives and mechanical

fasteners to suit Polymer Matrix Composites (PMCs)

Marine Industry

Carbon composites are considered in selected areas of marine industry in order to achieve high performance with least weight. Focused efforts are being pursued in the following areas:

? Generation of design and process data

comparable to design data sheets used for steel construction

? Development of material system and

designs

? capable of functioning in hot -wet

environments

? improved fire performance

characteristics

? good damage resistance ? Total integration of technologies ? Effective NDT techniques ? Cost effective and robust production

methods

? Low cost hull mould concepts in large

sized hulls (>100 meters long)

? Integrated approach in design, analysis,

testing, fabrication and assembly techniques.

External Document ? 2018 Infosys Limited

Oil and Gas Industry

Carbon fiber Composites are recognized as an enabling technology in deep-water and ultra-deep-water (1500m - 3000m) drilling scenarios. Many developments in areas of design, manufacturing, NDT have taken place. Some of the recent advances are

? A number of standards for

design, manufacture and testing, installation and maintenance were issued by European committee of standardization

? Cost effective routes for manufacture of

load bearing composites (main vertical and deck elements).

? Alternate designs, for example, in

the deck design, instead of sandwich construction a linked assembly of pultruded cellular elements construction to achieve the necessary degree of stiffness

? Developments in low cost

manufacturing processes, like, pultrusion of deep box beam section with fibers in different orientations.

? Development of resin infusion

moulding processes for very large components with high quality

? Reduction in carbon fiber costs

using cheaper precursors and better conversion technologies

Rail Industry

In order to meet the demands of high speed rail industry prototype vehicles are built using carbon composites. Recent advances in this area include:

? Standardization of Fire safety

regulations and issuance of harmonized standards for Fire, Smoke and Toxicity (FST) requirements

- Techniques for design, simulation and modeling of fire response

- Universal composite material system to meet stringent FST requirements

? Reduction in cycle time for

development and validation of nonlinear FE models for composites.

? Familiarization of engineers with

composites

? Cost effective manufacturing

techniques for:

? Industrial reproducibility at cost

levels comparable to steel

? Producing pre-equipped

subassemblies that can be assembled quickly to form a coach

? Generation of material and design

standards

? Generation of Approved performance

requirements

Wind Energy

Turbines blades are increasingly large to be cost effective which necessitates the use of carbon fibers. Recent advances include development of an integrated approach, combining processes, and material and design inventions. The areas of advances include:

? Multi-axial, multilayered matte/wove/

UD reinforcements

? Advanced pre-pregs to produce thick

sections of good quality eliminating the need for compaction

? Development of new core materials

that are

? Pre-preg compatible ? Suitable for resin infusion with low

resin absorption characteristics

? Higher thermal stability ? Epoxy resin reinforced with carbon

nanotubes resulting in half the weight of fiber glass blade

? Special thermoplastic coatings with

enhanced durability

? Thermoplastic composite materials and

processes

? Application of automated technologies

to shorten cycle times, increase precision and repeatability

? Automated Tape Layup (ATL) or

Automated Fiber Placement (AFP) processes

? Sophisticated measurement,

inspection, testing and quality assurance tools

External Document ? 2018 Infosys Limited

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